Adsorption of Cadmium Ions onto Zeolite-A prepared from Egyptian Kaolin using Microwave Technique

Zeolite-A has been prepared from Egyptian kaolin to remove divalent cadmium ion from wastewater. The synthesized zeolite was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A batch technique was employed as a function of temperatures, contact time and pH of the solution. Zeolite-A morphology was observed by SEM analysis, and it showed well-defined crystals slightly different sized crystals of the same cubic shape.Results revealed that the optimum conditions of the adsorption process are: zeolite dose= 0.25g in 25 mL of Cd(II) with contact time of 140 min, 333 K and pH 7.5.Two equations, namely pseudo-first order and pseudo-second order have been used to determine the kinetics of removal process.The collected kinetic data showed that pseudosecond order equations controls the adsorption.Chemisorption process and Langmuir isotherm proved best fitting to the experimental data.The adsorption mechanism was based on cation exchanges of Cd +2 ions present in wastewater and the available Na + ion.